Image reading apparatus

Abstract

An image reading apparatus is provided which includes a cold-cathode tube as a light source for illuminating a document sheet, an inverter for providing the light source with driving power. A connection cable is used for electrically connecting the light source to the inverter. The image reading apparatus also includes three kinds of rows of light receiving elements arranged in the primary scanning direction for detecting the light reflected on the document sheet. A lens array is provided for focusing the reflected light at the respective rows of light receiving elements. The light receiving elements are mounted on a printed circuit board. The light source, the inverter, the lens array and the printed circuit board are supported by a single case of the image reading apparatus.

What is claimed is:  
     
       1. An image sensor chip comprising: 
       a chip substrate;  
       a row of red light receiving elements formed in the chip substrate and arranged in a first direction for detecting red light, each of the red light receiving elements being covered by a red filter;  
       a row of green light receiving elements formed in the chip substrate and arranged in the first direction for detecting green light, each of the green light receiving elements being covered by a green filter; and  
       a row of blue light receiving elements formed in the chip substrate and arranged in the first direction for detecting blue light, each of the blue light receiving elements being covered by a blue filter;  
       wherein the red, green and blue filters have predetermined thicknesses, the thickness of the red filter being greater than the thickness of the green filter, the thickness of the green filter being greater than the thickness of the blue filter.  
     
     
       2. An image sensor chip comprising: 
       a chip substrate;  
       a row of red light receiving elements formed in the chip substrate and arranged in a first direction for detecting red light, each of the red light receiving elements being covered by a red filter;  
       a row of green light receiving elements formed in the chip substrate and arranged in the first direction for detecting green light, each of the green light receiving elements being covered by a green filter;  
       a row of blue light receiving elements formed in the chip substrate and arranged in the first direction for detecting blue light, each of the blue light receiving elements being covered by a blue filter;  
       a first amplifier for the row of red light receiving elements;  
       a second amplifier for the row of green light receiving elements; and  
       a third amplifier for the row of blue light receiving elements;  
       wherein an amplification factor of the first amplifier is smaller than an amplification factor of the second amplifier, the amplification factor of the second amplifier being smaller than an amplification factor of the third amplifier.